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Alendronate prompts atrial fibrillation warning

Their study found women taking alendronate were at an 86% higher risk of atrial fibrillation than those who had never used the drug.

It adds to concerns over the possible effects of bispohosphonates, after a trial published in 2007 of once yearly zoledronic acid reported atrial fibrillation as an unexpected adverse effect of treatment.

The researchers estimated as many as 3% of cases of atrial fibrillation in the population of older women studied could be explained by alendronate use. They insisted the benefits of the drug would still outweigh its risks in many women, but advised GPs to carefully weigh up those risks in more borderline cases.

Study leader Professor Susan Heckbert, a cardiovascular epidemiologist at the University of Washington, Seattle, said she had been conducting research into novel risk factors for atrial fibrillation when the trial of zoledronic acid reported – prompting her to reanalyse her data for alendronate.

But she cautioned that the findings, based on more than 700 women with confirmed atrial fibrillation and almost 1,000 controls, should not lead to mass changing of prescriptions. ‘For patients at high fracture risk, the benefits of fracture prevention will generally outweigh the possible risk of atrial fibrillation,' she said.

‘For patients at only moderate fracture risk, or those with risk factors for atrial fibrillation such as coronary disease or heart failure, they and their doctors will need to weigh the available information about risks and benefits carefully.'

The study, published in the latest issue of Archives of Internal Medicine, randomly selected women from the Group Health database. Some 6.5% of patients with atrial fibrillation had used alendronate, compared with 4.1% of controls.

But Dr Terry McCormack, a GP in Whitby and chair of the Primary Care Cardiovascular Society, urged caution over the findings. ‘I'd say there was a need for a prospective trial. This is an interesting observation but it's an important drug in terms of preventing fracture and there needs to be an evaluation of the real risk of atrial fibrillation and until then I wouldn't change anything.'

MSD referred Pulse to a statement from December 2007, in which it said: ‘We have re-reviewed data concerning atrial fibrillation in 28 placebo-controlled trials. In this preliminary analysis, observed incidence of atrial fibrillation was similar in patients receiving Fosamax (alendronate) compared with placebo.

Box: Key findings

- Women taking alendronate at 86% higher risk of atrial fibrillation than those who had never used the drug.

- Up to 3% of cases of atrial fibrillation in the population of older women studied could be explained by alendronate use.

- 6.5% of patients with atrial fibrillation had used alendronate, compared with 4.1% of controls.